The effect of variation in prey movement on the predatory response of Jacky Lizards (Amphibolurus muricatus)

Abstract

The sensory systems of animals have evolved to meet the demands of functionally critical events. Animals that rely on visual motion cues must ignore irrelevant movement and only attend to certain characteristics that warrant further consideration. For the Australian jacky lizard (Amphibolurus muricatus), movement is essential for detecting potential prey. Here we examine whether differences in the actual motion characteristics of a simulated prey item influence predatory behaviour. We begin with direct observations of responses to live prey items to define an ordinal scale for subsequent video playback experiments involving a synthetic prey item (an animated cricket). In expt 1, we show that the responses of lizards to the synthetic prey were matched to those given in response to video of an actual cricket. In expt 2 we manipulated the movement patterns of the synthetic cricket based on motion analysis of actual prey movement. Manipulating motion characteristics did not influence the level of predatory behaviour observed, however, lizards showed sustained predatory behaviour to stimuli with speed characteristics that were matched to those of real crickets. We discuss the possibility that recent experience of prey movement in captivity has influenced the foraging behaviour of these lizards.